The present invention relates generally to operations performed, and equipment utilized, in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides an expandable well screen.
It is useful in some circumstances to be able to convey generally tubular equipment into a subterranean well, position the equipment within a wellbore of the well, and then outwardly expand the equipment in the wellbore. For example, a restriction in the wellbore may prevent the equipment in its expanded configuration from passing through that part of the wellbore, but the equipment may pass through the restriction in its retracted configuration. In one application of this principle, it is known to use expandable well screens in wellbores.
An example of the potential usefulness of expandable equipment in a wellbore is where the wellbore intersects a productive, relatively unconsolidated, formation. It would be desirable in many situations to be able to utilize a well screen to filter production from the formation, while foregoing the expense of cementing casing in the wellbore and performing a gravel packing operation. Unfortunately, without any radial support the unconsolidated formation would likely collapse into the wellbore, causing additional expense and loss of revenue. Conventional nonexpandable well screens must necessarily be smaller than the wellbore in order to be conveyed therethrough, and so they are incapable of providing any radial support for an unconsolidated formation. Conventional expandable well screens are not designed for contacting and providing radial support for a formation, and so are unsuited for this purpose.
Therefore, it can be seen that it would be quite desirable to provide an expandable well screen which may be used for contacting and providing radial support for a formation intersected by a wellbore. It would also be desirable to provide an expandable well screen having enhanced torsional and tensile strength. It is accordingly an object of the present invention to provide such an expandable well screen.
In carrying out the principles of the present invention, in accordance with an embodiment thereof, an expandable well screen is provided. When radially extended downhole, the well screen may be used to support an unconsolidated formation. Of course, the well screen may also be used in situations in which a formation is not supported by the screen. Additionally, an expandable well screen having enhanced torsional and tensile strength is provided.
In one aspect of the present invention, an expandable well screen includes a generally tubular base pipe with a series of rows of holes formed through a sidewall of the base pipe, and a filtering media disposed externally on the base pipe. The holes of each row interconnect with each other, forming a larger opening, when the base pipe is expanded radially outward.
In another aspect of the present invention, an expandable well screen is provided which includes a generally tubular base pipe with a series of holes formed through a sidewall of the base pipe, and a filtering media disposed externally on the base pipe. The holes are distributed helically relative to a longitudinal axis of the base pipe. When the base pipe is expanded radially outward, each of the holes is compressed in the direction of the base pipe longitudinal axis.
In still another aspect of the present invention, an expandable well screen is provided which includes a generally tubular base pipe and an elongated strip of filtering media wrapped helically about the base pipe. The filtering media may be wrapped in multiple wraps about the base pipe, with a connection formed between adjacent wraps. The connection may be a welded seam between the wraps, or it may include a connector between the wraps. If a connector is used, various types of lines (electric, hydraulic, communication, chemical injection, etc.) maybe positioned adjacent the connector.
In yet another aspect of the present invention, an expandable well screen is provided which includes a generally tubular base pipe with alternating filtering media strips and expansion strips circumferentially distributed about the base pipe. The filtering media strips and expansion strips are connected to each other so that, when the base pipe is expanded radially outward, the expansion strips lengthen circumferentially, thereby increasing the circumferential separation between the filtering media strips.
In a further aspect of the present invention, an expandable well screen is provided which includes a generally tubular base pipe and a generally tubular filtering media outwardly overlying the base pipe. The filtering media includes expansion portions which permit circumferential lengthening of the filtering media. The expansion portions may be longitudinally extending corrugations formed on the filtering media. The screen may include longitudinally extending ribs positioned between the base pipe and the filtering media, and at least one of the ribs may be positioned between the base pipe and one of the expansion portions. One or more of the ribs may be substantially hollow and may have various lines (electrical, hydraulic, communication, chemical injection, etc.) extending therethrough. The filtering media may include a series of circumferentially extending and helically arranged slots, with a width of each slot decreasing when the base pipe is expanded radially outward.
In a still further aspect of the present invention, an expandable well screen is provided which includes a generally tubular base pipe, a filtering media outwardly overlying the base pipe, a series of ribs disposed externally relative to the filtering media and a generally tubular protective shroud outwardly overlying the ribs. An expansion strip may be connected to opposite circumferential ends of the filtering media, with the expansion strip elongating circumferentially when the base pipe is radially outwardly expanded, or the filtering media may have longitudinal corrugations formed thereon which at least partially straighten when the base pipe is radially outwardly expanded.
The filtering media in the above expandable well screens may include a layer of relatively fine filtering material sandwiched between layers of relatively coarse filtering material. The relatively fine filtering material may be a sintered woven filtering material. If the filtering media includes a woven material, the material may have strands thereof which are arranged helically relative to the base pipe longitudinal axis.
These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings.